Jointed strips of sheet metal and method of making same



Oct. y13, 1970 A A w. R. r-#uY-EAARv 3,533,891

JOINTED STRIPS oF SHEET-METAL AND METHOD `of' MAKING SAME Filed Dec. 7,1967 rA12/QAM Mw/ United States Patent O 3,533,891 JOINTED STRIPS OFSHEET METAL AND METHOD OF MAKING SAME Wallace R. Puyear, 5569 MaceriLane, Flint, Mich. 40507 Filed Dec. 7, 1967, Ser. No. 688,885 Int. Cl.B32b 3/22 U.S. Cl. 161-38 17 Claims ABSTRACT OF THE DISCLOSURE Theleading edge of a strip of sheet metal is joined to the trailing edge ofanother strip 'by a transverse strip of flexible non-metallic tapehaving reinforcing filaments running in an oblique angle with respect tothe width of the metal sheets.

This invention relates to the metal working field, and more particularlyto that aspect of the field in which long strips of sheet metal are fedto what are known as progressive die machines. Machines of this type areprovided with a series of dies, as many as twelve or more, each of whichdies represents a stage in the formation of a three dimensional objectfrom a flat strip of metal.

This metal is supplied to the fabricator in the shape of a coil whichmust -be fed into the progressive die machine in a step by stepoperation. At the start of operations metal must be fed completelythrough all of the die forming operations in the machine manually, afterwhich further stamping operations are continued with the strip being fedautomatically through the machine in step by step fashion after eachraising of the upper die holder. However, each time the machine comes tothe end of a coil of metal the machine must be stopped and the leadingedge of a succeeding sheet of metal must be fed into the machinemanually in the same fashion as the first sheet =was passed through themachine. In each case this advancing of the leading end of a strip mustbe done manually and is fairly time consuming Iby comparison with thenormal operating speed of the machine.

In order to reduce the time for introducing a new strip of metal intothe machine, various methods have been tried for attaching the leadingedge of a new strip to the trailing edge of the old strip in such amanner as to permit the new sheet to thread its way through the machineautomatically. One such method which has been tried comprises buttwelding the end of one strip to the end of the other, but this isunsatisfactory since the metal at the weld itself often is harder andless ductile than the remainder of the strip and, on occasion, when thiswelded portion of the two strips has ibecome positioned in one of thedies of the machine, the die has been damaged or even broken.

Another method of attaching two strips together has comprised the use ofa patching strip of non-metallic material, this patching strip beingadhesively secured to the two strips so as to bridge the joint betweenthe two strips. Non-metallic material which have been used for thispurpose include pressure sensitive tapes having reinforcing filaments ofhigh tensile strength material such as glass fiber, these reinforcingfilaments running longitudinally of the tape itself. However, when thesereinforced tapes have -been used they have been applied in the obviousmanner, with the reinforcing filaments running in the direction ofstress, namely along the length of the strip, since the purpose ofapplying the tape is to enable the leading strip to pull the followingstrip through the machine in the normal direction of travel.

However, it has been found that this latter method is alsounsatisfactory for the reason that there is always Patented Oct. 13,1970 lCe a tendency on the part of the two strips of metal to liex atthe point of junction between them. In practice, in view of the factthat the metal is comparatively rigid by comparison with the joiningtapes and that the supply roll may be located at a distance from themachine, a certain amount of bending normally does take place at thejoint with the result that the non-metallic tape material is forced toact as a hinge. The result is that the reinforcing fibers in the tapeare cut and broken by contact With the jagged edges of the two strips ofmetal.

Suprisingly enough it has been found that non-metallic tape, such as thecommercially available cellulose acetate pressure sensitive tapes havingclosely spaced longitudinally running glass filament reinforcingelements can be quite satisfactorily employed for joining the stripmetals with the reinforcing filaments disposed, not in the direction ofthe expected stress, but at an oblique angle with respect thereto. It isbelieved that the success of this type of joint is due to the fact thatany hinging action that may take place by relative bending of the twoadjacent sheets of metal is not transmitted to the reinforcing filamentsas a direct tensile stress Ibut only as a fractional component of thetotal stress.

Other objects and advantages will -be apparent to those skilled in theart after reading the following specification in connection with theannexed drawing, in which, FIG. l, is an isometric view of a supply rollof sheet metal having its leading end joined to the trailing end ofanother similar sheet of metal in accordance with the teachings of thisinvention; FIG. 2 is a plan view of an enlarged scale of the joint shownin FIG. 1; FIG. 3 is a crosssection on a still more enlarged scale takenon theA line 3-3 of FIG. 2, and; FIG. 4 is a cross-section taken on theline 4-4 of FIG. 2 and on the same scale as FIG. 3.

In the drawings, the numeral 10 indicates generally the trailing end ofa strip of sheet metal being fed to a machine, such as a progressive diemachine (not shown), and moving at a direction toward the right of thedrawing, as shown by the arrow. Numeral 11 indicates generally theleading end of a coil, indicated generally by numeral 9, of a new supplyof sheet metal joined to the trailing edge of the strip 10. Obviouslythe cross-sectional dimensions of the two strips 10 and 11 areapproximately the same so that the new strip will pass through themachine without difficulty.

While in normal practice the trailing edge 12 of strip 10 and theleading edge 13 of the following strip would be cut off on straightlines at right angles to the length of the strips, it is obvious thatthere will be occasional irregularities in the angles of these margins.In general the two abutting edges of the strips will be parallel to eachother. However in joining the two strips it has been desirable to leavea small gap, indicated generally by numeral 14, between the two margins,the width of this gap being approximately equal to the thickness of thesheets.

In one form of the invention the material used for securing the sheetstogether is a non-metallic tape having a pressure sensitive adhesivematerial on one side with a series of closely spaced reinforcingfilaments embodied in the tape or adhering to one side thereof andextending along the length thereof. f

Two such tapes suitable for the purpose are listed in the tape dataindex published by 3-M Manufacturing Company under the Scotch brand ofpressure sensitive tapes. These are identified under the heading ofAcetate Fiber, Film, filament tape numbers 890, 898, transparent glassfilament. Number 890 has a thickness of .008 inch and a tensile strengthof 500 pounds for a one inch wide tape with a stretch before breaking of3% of its length and is provided with a pressure sensitive adhesiverequiring 45 pounds to pull a 1 inch wide strip of tape from a steelsurface according to ASTM standard methods.

Number 898 has a thickness of .007 inch and a tensile strength of 340pounds for a one inch wide tape with a stretch of 3% and an adhesiveforce of 40 pounds for a one inch wide strip according to the testsrecognized by the ASTM. However, it should be understood that theinvention is not limited to the use of these specific materials.

While it is possible to provide a joint using the above mentionedpressure sensitive tapes applied directly to the metal it has been foundpreferable to apply a high performance contact type adhesive to themetal prior to the application of the tape. One such adhesive, althoughnot to be considered as limiting, is that produced in accordance withthe 3-M Company Products Specification No. 1357 dated Oct. l, 1966, andsold under the Scotch- Grit brand. Such a product basically comprises apolychloroprene base and initially has a consistency of a thin syrupwhich may be applied by either by spraying or brushing.

In making the joint the two metal strips and 11 are brought intoalignment with one another, as shown in FIGS. 1 and 2, with the margins12 and 13 adjacent but spaced from each other by the aforementioned gap14. Preferably the area adjacent the margins of the strips should beeither brushed or otherwise coated with a preliminary layer, indicatedby numeral 15, of a contact adhesive on both sides of each strip. Afterthe contact adhesive has been allowed to set the two longitudinallyextending tapes 16 may be applied along both surfaces of the sidemargins and the side edges of the two strips (as shown in FIG. 4) andextending across the gap 14 approximately equally along both adjoiningedges of the strips 10 and 11 and with the reinforcing filaments 17running in the direction of the length of the metal strips. In addition,the transverse tapes 18a and 18b will be applied bridging the gap 14,one tape being applied to each side of the strip of metal. In this casethe tapes 18a and 18b are arranged so that the reinforcing filaments 19aand 19b respectively, are disposed at an oblique angle with respect tothe gap 14, with the filaments 19a also being arranged at an angle withrespect to the filaments 19b of the tape on the reverse side of thejoint. In this way it will be seen that any flexing of the strips 10 and11 with respect to each other which would produce a hinging action aboutthe axis of the gap 14 will not produce a direct stress in tensionagainst the reinforcing filaments themselves. Any tendency towardsexerting pull on the tapes 18a and 18b in the direction of the length ofthe metal strips will produce only a comparatively minor component offorce in tension in the reinforcing filaments.

It has been found that even after repeated flexing of the strips 10 and11 that no breakage occurs in the tapes 18a and 18b and, surprisinglyenough, it has been found that the strength of these tapes is sufficientsuch that the longitudinally extending tapes 16 do not have theirreinforcing filaments destroyed either. Repeated tests have beenconducted on sample short lengths of metal bonded in this fashion bybending the strips about a 360 axes with respect to each other with nodestruction of the joint created in accordance with the teachings ofthis invention.

It should also be noted that While it has been stated that the tapes 16may be applied first, it is not considered an essential aspect of theinvention that this procedure necessarily be followed. It will beperfectly feasible to apply the transverse tapes prior to theapplication of the longitudinally running marginal tapes. It should alsobe observed that while, for the sake of clarity, in the drawing thetransverse tape is shown as extending across the gap only to the edge ofthe longitudinal tape, the transverse tapes 18a and 18b could extendentirely across the width of the metal strips either underneath or abovethe surfaces of the marginal joining strips 16.

Having disclosed one form in which the invention may be practiced itwill be understood that modifications and improvements may be made bythose skilled in the art which would come within the scope of theannexed claims.

I claim:

1. An article of the character described, comprising two strips of sheetmetal of indeterminate length and approximately the same thicknesspositioned in longitudinal alignment spaced from each other by a narrowgap and joined to each other by a transverse joining strip of fiexiblenonmetallic sheet material bonded to a surface of each of said metalstrips and bridging said gap, said joining strip including a pluralityof reinforcing filaments extending along axes disposed obliquely withrespect to the space defining said gap between the metal strips.

2. The invention as defined in claim 1, wherein said metal strips arebonded by a pair of transverse joining strips of flexible non-metallicsheet material bonded to the respective opposite surfaces of said metalstrips and bridging said gap, said joining strips including a pluralityof reinforcing filaments extending along axes disposed obliquely withrespect to the space defining said gap between the metal strips.

3. The invention as defined in claim 2, wherein the width of said gap isapproximately equal to the thickness of said metal strips.

4. The invention as defined in claim 1, wherein at least one of the sidemargins of each metal strip is also positioned in substantiallongitudinal alignment, and a marginal joining strip of non-metallicflexible sheet material having spaced reinforcing filaments is bonded tothe surfaces of the metal strips adjacent said adjoining side margins,the reinforcing filaments of said marginal joining strip extendingparallel with said margins.

5. The invention as defined in claim 4, wherein said metal strips are ofapproximately the same width and a second marginal joining strip ofnon-metallic flexible sheet material having closely-spaced reinforcingfilaments is bonded to the surfaces of the metal strips adjacent therespective other side margins, the reinforcing filaments of the secondjoining strip also extending parallel with the margins, both saidjoining strips extending around the respective opposite side edges ofthe metal strips and being bonded to both surfaces of each metal stripadjacent both side margins.

6. The invention as defined in claim 5, wherein said joining strips arecomposed of cellulose acetate material having glass filaments embodiedtherewith.

7. The invention as defined in claim 6, wherein said joining stripsinclude a pressure sensitive coating on one side thereof.

8. The invention as defined in claim 4, wherein said bond between themetal and the joining strips includes a contact adhesive.

9. Method of joining two strips of sheet metal of indeterminate lengthand approximately the same width and thickness, comprising the steps ofplacing said two sheet metal strips in longitudinal alignment and spacedfrom each other by a narrow gap; adhesively bonding a joining strip ofnarrow elongated non-metallic flexible sheet material having a pluralityof closely spaced longitudinally extending reinforcing filamentsembodied therewith to one surface of each said metal strip in atransverse direction adjacent said gap so as to bridge said gap acrosssubstantially the entire Width of the metal strip and to dispose thereinforcing filaments at an acute angle thereto.

10. The method as defined in claim 9, which includes the additionalsteps of adhesively bonding a second said joining strip to the oppositesurfaces of each said metal strip to bridge said gap and to dispose thereinforcing filaments of the second joining strip at an acute anglethereto.

11. The method as defined in claim 10, which includes the step ofdisposing said second joining strip in a transverse direction angularlyrelated to the transverse direction of the first joining strip.

12. The method as defined in claim 11, wherein said 5 joining strips arecomposed of a cellulose acetate material having glass filaments embodiedtherewith.

13. The method as defined in claim 9, which includes the step ofapplying a coating of contact adhesive to said sheet metal strips forbonding said joining strip thereto.

14. The method as defined in claim 9, which includes the step ofapplying a pressure sensitive adhesive coating to said joining strip andbonding said joining strip to thc metal strips by the application ofpressure thereto.

15. The method as defined in claim 11, which includes the steps ofapplying to the metal strips an additional pair of joining strips ofnon-metallic flexible sheet material having a plurality of closelyspaced reinforcing filaments embodied therewith, and bonding saidjoining strips to both surfaces of the side margins of the metal stripswith the reinforcing laments extending longitudinally of the length ofthe metal strips.

16. The method as defined in claim 15, which includes the application ofa coating of pressure sensitive adhesive to said joining strips, and theapplication of pressure to said strips for said bonding to the sheetmetal strips.

17. The method as defined in claim 5, which includes the step ofapplying a coating of contact adhesive to said metal strips prior tobonding said joining strips thereto.

References Cited UNITED STATES PATENTS

